1. Field of the Invention
The present invention relates to an apparatus for conveying untreated materials, wherein the untreated materials are conveyed from a treating section to another in an electroplating system, a painting system or the like including a row of treating sections into which the untreated materials are conveyed in turn to be treated in a given treating manner.
2. Description of the Prior Art
Apparatus of the above-mentioned type have been used, for example, to convey materials or workpieces to be electroplated in turn in electroplating workshops. As well known, the electroplating treatment includes many treating steps performed in sequence. Accordingly, the materials to be electroplated are conveyed by a conveying apparatus from each treating section to another in turn. Such conveying apparatus of the elevator type is known. In the elevator type conveying apparatus, the materials are hung on carrier bars bridged over opposite edges of treating tubs and lowered into the treating tubs. A pair of elevator frames are provided on opposite sides of the treating tubs along the treatment line. The elevator frames are movable vertically, and when moved upwardly, the elevator frames are adapted to lift both ends of each carrier bar, thereby carrying the materials out of the treating tubs. A part of each elevator frame supporting the carrier bars is movable transversely (or along the treatment line) and moved transversely with the materials carried out of the treating tubs so that the materials are conveyed to areas over the subsequent treating tubs, thereby lowering the materials into the treating tubs.
According to the above-described elevator type apparatus, when the elevator frames are operated at one operation cycle of upward, transverse, and downward movements, all the materials placed in the zone of movement of the elevator frames are collectively conveyed. Therefore, the elevator type conveying apparatus has a high conveyance efficiency and is suitable for mass production of a few kinds of workpieces. The elevator type conveying apparatus, however, has the following disadvantages. First, since a feed pitch of each elevator frame is constant at any position, the treating tub for treatment requiring a long period of time is necessarily rendered large-sized in proportion to the treating period, resulting in a large-scaled treatment line. For example, when the electrolytic degreasing, acid pickling, and electroplating require 10 seconds, 20 seconds, and 10 minutes (600 seconds), respectively, the length of the acid pickling tub in the direction that the materials are conveyed takes the value of 1 meter, and that of the electroplating tub the value of 30 meters when that of the electrolytic degreasing tub takes the value of 50 centimeters. Secondly, it is rather difficult to omit or skip over a part of the treating steps depending on the materials to be treated. Even if some of the treating steps can be omitted or skipped over, the production period of time cannot be shortened since the materials are conveyed at a given pitch.
On the other hand, a carrier type conveying apparatus, which is quite different from the foregoing elevator type, has been commercially produced. Travelling rails are provided over the treatment line, and a carrier is movable along the rails to any position. The carrier is moved from one treating tub to an area over a next treating tub with the materials hung on the carrier, thereby lowering them into the treating tub.
According to the carrier type conveying apparatus, the materials may be conveyed to and placed in any treating tub :or any period of time. As a result, a plurality of kinds of materials having different treating steps may be conveyed. Furthermore, the length of the treatment line may be shortened. However, since a unit of materials need to be always conveyed, the conveyance efficiency is reduced, resulting in reduction of the productivity thereof.
As described above, the conventional elevator type conveying apparatus causes the treatment line to become large-scaled, while it is superior in the conveyance efficiency. Furthermore, it has a disadvantage of lacking adaptability in combination of the treating steps.
Although the carrier type conveying apparatus is superior in the shortening of the treatment line and the adaptability in combination of the treating steps, it is inferior in the conveyance efficiency.